Barry,
I don't think your opinion that the camber compensator restricts wheel movement
is a correct one. It has a center pivot point much
like the swing spring that allows the axles to achieve full travel.
My observation is that the swing spring (while achieving its design function)
creates as many problems as it solves. Perhaps not in
the short run, but certainly in the long run. Witness the spring sag evident
on most of the later Spits that have their original
spring. Then look at any earlier fixed spring Spit and see if you can see any
sag.
Then there is that issue of roll stiffness. I don't believe for an instant
that reducing it does any good for vehicle handling. If
the wheel tuck can be controlled without reducing roll stiffness, then I firmly
believe that is the correct path to take. Plus, the
redesign of the spring must have been horribly expensive for a company already
strapped for cash at the time. I have to believe it was
a case of, "not invented at home" that kept the camber compensator from being
adapted on the later spits.
That said, I admit to having a swing spring installed on Huxley the Mk1. But
when I get the time To rebuild the Monza exhaust so it
doesn't interfere, I plan to retrofit the original fixed spring and camber
compensator. But the swing spring does perform its intended
function adequately. However, it is considerably more expensive to update to
that than it is to add the camber compensator.
Regards,
Joe
Barry Schwartz wrote:
>
> I wasn't going to say anything, and I don't wish to start or will not enter
> into an on list flaming war, but I must chime in here.
> The Swing spring is a very elegant engineering and production solution to a
> potentially serious problem with swing axles. I don't think it should be
> de-rated because of personal preference. I'll add this is just my opinion.
> There is a WHOLE lot more to making a car handle that making a car stiff in
> the roll axis. If that were the end all one would simply do away with
> suspension all together and bolt the wheels directly to the frame. As with
> almost everything in design it's a compromise - Swing axles really DON'T
> like a lot of roll stiffness, because this leads to the dreaded tuck under
> during spirited cornering in the first place. That is one reason that you
> want REDUCED roll stiffness at the rear with a swing spring type suspension
> and remember it was made up for in the front by a stiffer front roll bar.
> This was done by changing the spring mounting system in the Spitfire,
> WITHOUT limiting wheel travel, something that I don't believe can be said
> for the camber compensator.
> REMEMBER, this is a production vehicle driven on the street by the general
> public. While a camber compensator may do the trick, and possibly has it's
> place particularly in racing circles, where streetability can and is
> compromised on a regular basis for the sake of handling, the Swing spring
> was and still is an exceptional solution to a streetable, production
> vehicle. It did the job exceptionally well without undue cost - I don't
> see anything inherently bad or wrong with that.
> The reason that the later MK3 GT6's were converted to the "less desirable"
> (not my words) Swing spring was again simply and purely a cost reduction
> measure. The Swing spring was *almost* as good as the Rotoflex suspension
> at controlling wheel tuck and in handling for a production vehicle, so the
> decision was made to fit the cheaper Swing spring which was and I quote
> "almost as effective" as the Rotoflex suspension but at a reduced cost. As
> a corporate decision concerned with rising costs on a limited production
> vehicle there was really no question what was necessary to do -
> The only thing I remember in reading the competition manual for the GT6 was
> to replace ONLY the spring on the Rotoflex models with the Swing spring,
> not the entire suspension. Unless I misread or remember incorrectly which
> is a distinct possibility :-).
> There is really NO question as to which suspension is superior at
> controlling the rear of a Spitfire or GT6. The Rotoflex fully independent
> setup with lower control arms is the best of the bunch. . . period.
> Kas's solution (the camber compensator) WAS a compromise, not an end all,
> just as all other designs are. I'm sure if you asked him he would tell you
> that. It just depends upon WHAT you are willing to compromise. I respect
> Kas's opinions very much, and don't de-rate the camber compensator at all.
> I believe he may have a personal pride, preference etc. in a system he
> (helped) develop which is not unreasonable, but at the same time (and this
> stems from being a mechanical designer most of my life) I also believe
> there may be other solutions that could be just as good possibly even better.
> ***************************************************
> < original message >
> > Now I see where you are coming from. Bear in mind that those documents
> were all produced after the introduction of the swing spring
> >and after the camber compensator was discontinued. In other words, it was
> "the only show in town", so there was nothing to compare
> >against. Still, it doesn't explain why anyone, particularly someone in
> the Triumph Competition Department) would recommend replacing
> >the rotoflex with the swing spring. Apparently the factory was really
> proud of the needless investment in R&D that yielded the swing
> >spring.
> >
> >They tackled a problem (Wheel tuck) by reducing one of the superior traits
> of the Spitfire, which of course is outstanding roll
> >stiffness. Kas' very simple and effective solution didn't take away from
> roll stiffness but attacked the problem, not the symptom.
>
> Barry Schwartz (San Diego) bschwart@pacbell.net
>
> 72 PI, V6 Spitfire (daily driver)
> 70 GT6+ (when I don't drive the Spit)
> 70 Spitfire (long term project)
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